After Toxic Beaches and Waterways, Florida Eyes Septic Tank Upgrades

Officials increasingly want to move away from underground waste storage systems, which can leak chemicals that fuel toxic algal blooms.

Florida red tide beach
Red tide and algal blooms closed beaches in Florida last year. Some experts say septic systems are worsening those sorts of environmental problems.
(AP/Lynne Sladky)


  • Nearly 2 in 5 Floridians rely on septic tanks instead of sewer systems. The waste disposal tanks could be doing serious harm to the state's fragile ecosystem.
  • Some experts blame septic tanks for the rise in Florida's recent environmental problems, including algae blooms and foul-smelling rivers. Climate change and rising sea levels could exacerbate the problem even further.
  • Replacing septic tanks with sewer system connections is extremely expensive. It would cost an estimated $3.3 billion for Miami-Dade County alone. But another South Florida is in the process of phasing out septic tanks entirely.
When Florida Gov. Ron DeSantis gave his inaugural speech earlier this month, he channeled Winston Churchill to rally Floridians to join the fight for clean water.

“I will lead the efforts to save our waterways,” the Republican governor vowed, citing a long list of natural disasters that have plagued Florida’s rivers, lakes and coastal waters, many just in the last year. Floridians have recently had to contend with red tide in the Gulf of Mexico, toxic and slimy blue-green algae in the state's rivers, and brown sargassum seaweed off the Atlantic Coast.

“We will fight toxic blue-green algae,” DeSantis said. “We will fight discharges from Lake Okeechobee, we will fight red tide, we will fight for our fishermen, we will fight for our beaches, we will fight to restore our Everglades and we will never ever quit, we won’t be cowed and we won’t let the foot draggers stand in our way. We resolve to leave Florida to God better than we found it.”

But the fight that DeSantis promised, despite its lofty rhetoric, will not be fought in the skies or the streets or the fields or the hills. Much of it will be fought in the dirt, with septic tanks, the underground sewage disposal networks, as the key targets.

Brian LaPointe, a professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, has been warning Florida residents of the dangers of septic systems to the state’s fragile aquatic environments since the Carter administration. But his message has gained traction in the last few years, especially since the Florida Chamber of Commerce started promoting it.

LaPointe says the biggest reason for the algal bloom, fish kills, goopy water and awful smelling rivers over the last few years has been contamination from septic systems. Nearly two out of every five Floridians rely on septic tanks. “These local governments cannot do this on their own. They need help,” he told Florida senators this month. “We need a Manhattan Project. We’ve got to go to war against algae.”

Unlike sewers, which whisk dirty water away through pipes to a water treatment center, septic tanks filter the water on-site. They sort the waste into three layers -- scum, sludge and wastewater. Bacteria eventually break down the scum at the top of the tank, while sludge falls to the bottom. (Sludge has to be pumped out periodically for the septic tank to work properly.) The wastewater, or effluent, sits in between the scum and the sludge. It flows into underground pipes near the tank and is released into the ground in an area called the drain field. Cesspools are similar to septic tanks, but more primitive. The systems rely on the natural filtration of the soil to eliminate the worst contaminants in the water.


Have Septic Tanks Caused Environmental Problems in Florida? 

There’s still quite a bit of debate in Florida over the cause of the recent algae blooms. Many environmental groups focus more on fertilizers used in large-scale agriculture, such as sugar plantations, as a source of high nitrogen and phosphorous levels in the water. They also say that more freshwater should be filtered through wetlands like the Everglades to clean the water of harmful nutrients.

LaPointe chafes at those arguments. He says major farming operations have reduced the amount of fertilizer they use and have stopped using fertilizer completely during the rainy season. He also points out that the Tampa Bay and Sarasota Bay regions restored their once algae-choked waters by taking a hard line on discharges from wastewater plants and the installation of new septic tanks in their watersheds.

The reason why 2018 saw so many algal blooms in the rest of Florida, he says, is because Hurricane Irma saturated much of the state and overwhelmed its septic tanks. Because of Florida’s high water table, septic systems are often placed too close to groundwater. Heavy rains can force the ground water up, into the tanks and out into rivers, along with all of the contaminants that the septic systems were supposed to gradually remove from the wastewater.

What’s more, climate change could be making that problem worse, because sea-level rise will push groundwater higher. A recent report by Miami-Dade County concluded that 64 percent of its septic tanks will regularly fail by 2040, up from 56 percent today.

Doug Yoder, the deputy director of Miami-Dade’s water and sewer department, says rising ground water levels can harm the environment even before the ground water gets into a septic tank. The closer the ground water gets to the septic tank, the less dry soil there is to filter the effluent coming out of the septic tank. That means the water is dirtier when it gets into the groundwater supply. Once the ground water gets into the septic tank, it can cause pooling of sewage on the ground or sewage backups in the building attached to the septic system.

The county report estimated that it could cost $3.3 billion to replace the 100,000 septic tanks with sewer line connections.

“The problem has been that it is expensive to extend water and sewer systems to areas that are already built. It’s much less expensive to build sewers when the land is first being developed,” Yoder says. “When you have to go back and tear up every street and avoid utilities that are already in place in order to provide water and sewer service at today’s prices, it’s extremely expensive.”

Because the expenses are so high, Yoder says, local officials have to make sure that upgrades to sewer connections make sense. You don’t want to spend hundreds of millions of dollars to install new sewers, only to find out that the nitrogen or phosphorous causing algae blooms is coming from a different source. That’s one reason why Miami-Dade officials plan to do a follow-up study that focuses on the environmental impacts of the septic systems.

The environmental impact is only one consideration, though, Yoder says. If a piece of property is flooding so much that it needs a sewer system to avoid septic field contamination, it may not be viable much longer as a place to live.


Getting Rid of Septic Tanks Altogether

A little farther north of Miami on the Atlantic coast, one county is moving to eliminate its remaining 10,000 septic systems over the next decade. Residents will have to pay between $8,500 and $9,000 for the service, and the county will pick up the remaining costs of the installations, which usually cost around $15,000 total, says Martin County Commissioner Doug Smith.

Martin County has been inching toward the goal for a long time. It has long required developers to pay to connect new homes to existing sewer lines. That benefitted both the new development and homes along the route of the new sewer lines, which could then hook up to sewers for much cheaper once the new lines were installed.

But Smith says two “horrific” seasons of blue-green algae growth in 2016 and 2018 convinced county officials to finish off the job. “There’s an enormous awareness that we have to do it better,” he says.

So far, Smith is encouraged with the steps the governor has taken on the state level to address the blue-green algae blooms. Smith hopes DeSantis and state lawmakers can set aside $50 million a year for matching grants to help counties and municipalities convert septic tanks to sewer hook-ups. He wants them to fund a pilot program to help counties treat biosolids that are widely used in fertilizers, in order to remove the nitrogen and phosphorous that lead to algae blooms. And he thinks that the state needs to plan for its water infrastructure in a more systemic way, more like the way that it plans on and pays for road infrastructure.

“We just cannot continue to do what we’ve done. We can’t exist through three or four months of hellacious conditions every summer,” Smith says. “The governor clearly understands that. I’m hoping legislature understand it. It’s not about blame, it’s about how we fix it.”

This appears in the Infrastructure newsletter. Subscribe for free.

Dan is Governing’s transportation and infrastructure reporter.